Spark plug



July 9, 1929. G. M. PAULSON SPARK PLUG Filed April 4, 1927 Patented July 9, 1929.

UNITED] STATES 1,719,848 PATENT, OFFICE.

ononon m. PAULSON, or

ASTORIA, NEW YORK, ASSIGNOR TO THE B. G. CORPORATION,

A. CORPORATION OF. NEW YORK.

SPARK PLUG.

Application filed April 4,

This invention relates to spark plugs and more especially to that type of spark plug having a spindle or the like extending throughout the length of the plug.

in object of this invention is a.composite spindle that will stand the heat and strains to which a spark plug spindle is subjectedf According to this invention, the major portion of the spindle is composed of metal of good heat-conducting qualities at one end of which is carried a head of a metal having nonscaling properties at the temperature attainedwithin the combustion chamber of an.

engine and of suflicient compressive strength not to lose its shape under combustion conditions. In the head is mounted a sparking point which is resistant to erosion under the conditions of electrical discharge and combustion.

Other objects, novel features and advantages of this invention will be apparent from the following specification and accompanying drawings wherein Figure 1 is a verticalsection through a spark plug equipped with a spindle embody-- ing the 1nvention;

Fig. 2 discloses a step in the formation of the spindle;

Fig. 3 discloses the finished spindle;

Figs. 4 and 5 show a modified form of the composite spindle; and

Fig. 6 is a sectional view of a plug having a modified form of orifice.

Referring now to Fig. 1, 10 is the body of the plug which is threaded to be screwed into a suitable socket. Screwed into the body 10 is a hollow bushing 11 which insulatingly supports the spindle 12 in the manner set forth in the co-pending application of applicant and ltoy T. Hurley. i

The spindle comprises a cylindrical shank 13 composed of a metal having high heat conducting properties and also having good physical and tensile strength as well as suflicient elasticity to allow for and to withstand the expansion and contraction of the insulators which comprise parts of the spark plug. head 14 is carried by the spindle 13 at its lower end. This head when the spark plug is in use is subjected to the combustion conditions in the cylinder of the engine and the resultant heat. It is essential that this head he composed of a metal having non-scaling properties when subjected to the combustion conditions and have suflicient compressive 1927. Serial No. 1sh,7s s.

strength as not to flow or lose its shape under combustion conditions and be of sufiicient tenslle strength to resist expansion of the insulators which are located above the head. A sparking point 15 is mounted in the head 14 and 1s composed of metal resistant to erosion under the conditions of electrical discharge and combustion.

Steel known as S. A. E. 1020; that is, a carbon steel having10-20 point carbon, has been found suitable for the shank 13. The head 14 is preferably composed of chromium steel. For example, Ascaloy No. 1 and the sparking point 15 is preferably composed of a manganese nickel alloy.

The shank 13 and head 14 may be joined toa operation is preferably performed before the head 14 is given its final shape. This arrangement brings the heat-conducting metal as close to combustion conditions as possible without exposing the surface of the same to the actual combustion conditions.

The structure above described provides a composite electrode having heat-conducting metal in the parts out of actual contact with the combustion gases and a metal which will not scale under combustion conditions in that part of the electrode which comes into actual contact with the combustion gases. .It is apparent, of course, that metals different from those specifically mentioned may be utilized so long as they have the desired properties without in any way departing from the spirit of the invention as set forth in the appended claims.

In Figs. 4 and 5, I have illustrated a modified form of composite spindle, wherein the shank 13 of the spindle is welded to the head 14 at the point 16 exterior to the head proper. This is advantageous in certain types of A plugs.

tion. The baflle preferably is made of the same steel as the jacket. Such steel will get red-hot and tend to burn the oil, thus preventing fouling. The baflle plate serves not only to prevent'the oil from going up into the spark plug, but tends to prevent fouling of the sparking point and of the plug adjacent the sparking point. In the particular construction shown in Fig. 6, the outside electrode is drilled through the shell wall and the bafile plate, the-latter having good electrical causing missing and skipping of the engine.

I claim:

1. In a spark plug, a composite Spindle comprising a shank composed of heat-conducting metal, a head composed of heat-resisting metal, and a sparking point mounted in said head composed of a metal resistant to erosion under electrical discharge conditions.

2. In a spark plug, a spindle comprising a shank composed of carbon steel, a head composed of chromium steel and a sparking point mounted in said head, said sparking point being composed of a manganese nickel alloy.

In testimony whereof, I have signed my name to this specification.

GEORGE M. PAULSON. 

